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Offset Timing Keys--Should they be used with an EFI???

We get a number of calls regarding the use of an offset timing key in EFI vehicles. There are a number of issues that need to be addressed when you are doing this type of modification.

We have listed them below:

1) The EFI systems are driven electronically. When you install an offset timing key in an EFI, you are not only altering the timing of the ignition, but also the timing of the fuel injection system itself. This is because both parts of this system are fired from the same trigger.

2) The use of an offset timing key will change the temperature in the pipe and may require a different clutch calibration to compensate for this.

3) Generally speaking, the use of advanced timing will lower the peak RPM, to a level that is not consistent with the original peak. This is due to the lack of overall pipe heat at the peak RPM. IE: Hot pipe- higher Peak.

4) Use of an offset timing key will be advancing the timing in a linear manner, the equal amount from the bottom to the top. This can cause extremely hot midrange areas in certain engines.

Most of our calls have been in regard to the use of offset keys in the new F7 vehicles. Armed with the above information, we can tell you what we have experienced. The use of an offset key definitely produces more horsepower on the dyno. It raised it by a consistent 2.0 to 2.5 HP. This testing of course was done in a controlled environment and with a full load on the engine.

Although we had no snow in TRF when these tests were completed, some of our customers had ice and were willing to make this installation and see if it affected performance. Prior to installation, the customer's F7 seemed to be a rocket ship, it ran at 7900-8000 and top speeds were in the 115-116 mph range, consistently, on the radar gun. Following the installation of the key, the top speed fell to 113-114 mph, with the sled feeling like it was surging at peak, in addition to losing between 300 and 400 RPM. It was hard to start and according to the owner--it just felt funny. This comparison was done on the same day and at the same location--although not as scientific of a test as some would like---it was a direct comparison none the less.

Why did this happen?? Evidently, the advanced timing caused the pipe to be a bit colder and it did not want to come up to temperature properly and the actual peak did come down. The surging the customer referred to, we call "yo-yoing", and is caused by a pipe that is acting too big or simply not up to temperature. Sometimes this can be cured by clutching the vehicle heavier, to load the engine more and cause the pipe to heat up more consistently.

In closing, is it a good idea to be adding an offset timing key to an F7? This is what we were told by the person from Arctic Cat who did the calibration on the entire EFI system, "We made the timing curve as aggressive as we felt was possible on the sled. If additional timing is installed, it may very well cause engine damage at trail speeds, and definitely causes the pipe to act cold at full throttle." Well, there you have it---our dyno test results---a customer report---and words of wisdom from the manufacturer.

It is a free world---you can decide for yourself if this is the way to go.
 

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V- force 3,s will out run a stock F-7 by 5 to 6 lengths in 500'
Install a orange-white cat spring. The stock clutching is DAMM CLOSE!!!!!!!!!!!!!
I Also installed a 02 snopro airbox, much lighter and not NECKED DOWN at the box intake!
Will touch 120mph with these mods, use 92 oct. gas.
TRYED AND TRUE!!
 
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